crash course ANS

the nerve fibers of your parasympathetic nervous system begin both above & below where the sympathetic ones do. they're craniosacral, meaning they sprout from the base of your brain and also from your sacral spinal cord, just superior to the tailbone

because the roots of the nerve fibers basically frame the starting points of the sympathetic nerves, they were called parasympathetic ----literally "beside the sympathetic"

ANS is...

branch of the motor division of the PNS that regulates the functions of your internal organs like your heart and stomach, and also controls your smooth & cardiac muscles & your glands (unconscious control)

where are sympathetic ganglia found?

closer to the spinal cord because in those fight-or-flight moments of high excitement or activity, they need to be able to send a single message far moments of high excitement or activity, they need to be able to send a single message far and wide. this way, the excitatory signals traveling into a ganglion near the spine---ganglion being the singular ganlia---can trigger action potientals in a whole bunch of other neurons that lead to many different effectors, like the heart, lungs, & stomach and adernal glands.

ganglia

clusters of neuron cell bodies that house millions of synapses

the ANS's effects on your organs and muscles and glands are by no means _______

consistent

the nerves of the two regions originate at _______ _______ in your body

different sites

your ANS is constantly making involuntary, fine-tuned adjustments to your body based on what signals your central nervous system is picking up

examples: 1. changing your body temperature 2. sending blood to a particular area 3. slowing your heartbeat 4. tweaking your stomach secretions

your sympathetic system is what sounds your internal alarm bells

flight or fight

most parasympathetic gangilia are found way out from the spine --- near, or even inside their effector organs this system is responsible for taking care of particular functions only when you have the time and energy to do it---like digesting food or secreting waste--- it uses more specific, strategic signals

found way out from the spine, near, or even inside, their effector organs

what's the difference between the PS and the S?

ganglia

in the sympathetic system, the preganglionic fibers are much shorter than the postganglionic ones

ganglia are close to the spinal cord and the axons don't have, or need, very far to go from the central nervous system. but they do have a lot of distance to cover, the other side of the ganglion, in order to reach their effectors. so naturally the fibers leading out of the ganglia are a lot longer.

PNS is responsible for....

maintaining your body and conserving energy for later

parasympathetic is like a private call

not everyone needs to be involved; only communicates with organs needed

the PS's and S's neurons themselves have slightly different forms, namely the length of their axons

now ganglia can be kind of complex Greek for a "knot in a string"

sympathetic nervous system fiber's are thoracolumbar, which means that they _____ from between your thoracic vertebrae where your ribs attach, and the lumbar vertebrae just inferior to your ribs

originate

and the other one talks your down and effectively undoes what its foil did

parasympathetic nervous system

the parasympathetic is for....

rest and digest

ANS's effects change depending on the situation you're in and which part of your Autonomic system is in charge at that moment

run by two competing interests two divisions that serve the same organs, but they opposite effects in them, battling it back and forth, to either excite your body's functions or subdue them

one of them is dedicated to amping you up and preparing you for activity

sympathetic nervous system

postganglionic cell

the neurons after the ganglion

preganglionic cell

the neurons before the ganglion

since parasympathetic ganglia are so close to, or even inside of, their effector organs, the preganglionic fibers are a lot longer

they extend from the cranium and sacrum where they start, out to other lungs or liver or bladder or wherever their effector is---where they reach their ganglion from there the postganglionic fibers are super short--just long enough to communicate with their effector

the ANS is run by two competing interest

two divisions that serve the same organs, but they create the opposite effects in them they are battling it back and forth, to either excite your body's functions or subdue them one of them is dedicated to ampione of them is dedicated to amping you up and preparing you for activityng you up and preparing you for activity

unlike your sensory or motor neurons; where a single axon can reach all the way from your spinal cord to whatever muscle or touch receptor it works with, both parts of your autonomic system require........

two neurons to work

the two competing systems differ chiefly in:

1. sites of origin of neurons from the CNS 2. relative lengths of their fibers 3. location of their ganglia